The status and behavior of the microcirculation will be assessed initially in vascularly isolated denervated hind limb muscle and then in progressively more intact preparations until a procedure applicable to clinical use is achieved. By utilization of the mass balance relationship for plasma proteins, it should be possible to obtain relative assessments of pre- and postcapillary resistances, capillary pressure-surface area, capillary permeability, vascular capacitance, and interstitial volume. This will require critical assessment and validation of the mercury-in-rubber strain gauge for the identification of volume changes and venous blood colloidal osmotic pressure as a specific indication of hydrostatic transcapillary fluid movement.